1. Field of the Invention
The present invention relates to wireless links in a network, such as wireless links to an intermediate network node orbiting the earth on a satellite.
2. Description of the Related Art
Networks of general-purpose computer systems and other devices connected by external communication links are well known and widely used in commerce. The networks often include one or more network devices that facilitate the passage of information between the computer systems and devices. A network node is a network device or computer system connected by the communication links. As used herein, an end node is a network node that is configured to originate or terminate communications over the network. In contrast, an intermediate network node facilitates the passage of data between end nodes.
Some networks include two or more intermediate network nodes that communicate with each other over one or more wireless links. Some wireless links called point-to-point wireless links are dedicated to communications between two particular intermediate nodes, such as by dedicating a particular electromagnetic frequency to such communications. Changing environmental conditions can adversely impact propagation of electromagnetic carrier waves that provide that wireless link and can reduce a signal to noise (S/N) ratio of signals received over that wireless link, thus interfering with passage of data packet traffic over the wireless link.
Corrective action includes automatically detecting the reduction in S/N ratio and automatically increasing power of transmission (e.g., automatic gain control). However, there are practical limits to the power increases that can be applied. For example, some noise components, such as scattering, are proportional to power and thus rise with the increase in power. As a further example, one or more components of an intermediate network node are designed for a maximum operating power and will fail when power levels exceed that maximum. Furthermore, some intermediate nodes have access to limited sources of power. On earth orbiting satellites, especially, power supply is severely limited.